Analysis of longitudinal data with drop-out: objectives, assumptions and a proposal

Summary. The problem of analysing longitudinal data that are complicated by possibly informative drop-out has received considerable attention in the statistical literature. Most researchers have concentrated on either methodology or application, but we begin this paper by arguing that more attention could be given to study objectives and to the relevant targets for inference. Next we summarize a variety of approaches that have been suggested for dealing with drop-out. A long-standing concern in this subject area is that all methods require untestable assumptions. We discuss circumstances in which we are willing to make such assumptions and we propose a new and computationally efficient modelling and analysis procedure for these situations. We assume a dynamic linear model for the expected increments of a constructed variable, under which subject-specific random effects follow a martingale process in the absence of drop-out. Informal diagnostic procedures to assess the tenability of the assumption are proposed. The paper is completed by simulations and a comparison of our method and several alternatives in the analysis of data from a trial into the treatment of schizophrenia, in which approximately 50% of recruited subjects dropped out before the final scheduled measurement time.     

The impact of welfare reform on the parenting role of women in rural communities

Current family policy suggests that in order to restore family values we, as a society, need to focus on reviving a child-centered household. Full-time mothering is lauded as an honorable choice that will advance this goal and ultimately strengthen traditional family values. However, current welfare policy is contrary to this notion in that mandatory welfare-to-work programs deny women receiving public assistance the choice to be full-time mothers. Based on in-depth interviews with female welfare recipients in four rural Appalachian counties, this paper evaluates the problems women face as they confront the difficult choices of being either a “good mother” or a “good recipient.” From a feminist perspective, findings suggest that welfare reform programs in rural communities have put poor women in a proverbial “catch-22” with regard to effective parenting. Although many of the women strive to be ideal mothers as defined by societal standards, they often find that they cannot carry out the role effectively because of welfare reform regulations.     

NGOS AND THE DEVELOPMENT OF CIVIL SOCIETY IN BULGARIA AND THE USA

This study examines the development of civil society and its ability to facilitate stronger democratic practices in Bulgaria using the USA as a comparison. Using data gathered from surveys of NGOs in 2006, we examine three sets of questions. First, what is the level of NGO organizational capacity? Second, to what degree are NGOs performing their mediating roles? Third, how do NGOs perceive their effectiveness in working with the state and its citizens. Our findings suggest that Bulgarian NGOs face a number of challenges when compared with US NGOs, which affect their ability to engage in civil society activities such as establishing horizontal ties with citizens and other groups.     

Emergency and Disaster: Pervasive Risk and Public Bureaucracy in Developing Nations

Developing nations experience pervasive risk of devastation, human and property loss resulting from human and natural disasters. This level of risk is attributable to socioeconomic stress, aging and inadequate physical infrastructure, weak education and preparedness for disaster and insufficient fiscal and economic resources to carefully implement the preparedness, response, mitigation and recovery components of integrated emergency management. This article examines these dynamics using a conceptual framework derived from chaos theory and emergency management theory and raises several critical methodological issues related to inquiries into disaster and emergency management dynamics in developing nations.     

Broadcasting multiple messages in the 1-in port model in optimal time

In the 1-in port model, every vertex of a synchronous network can receive at most one message in each time unit. We consider simultaneous broadcasting of multiple messages from the same source or from distinct sources in such networks with an additional restriction that every received message can be sent out to neighbors only in the next time unit and never to already informed vertex. We use a general concept of level-disjoint partitions developed for this scenario. Here we introduce a subgraph extension technique for efficient spreading information within this concept. Surprisingly, this approach with so called biwheels leads to simultaneous broadcasting of optimal number of messages on a wide class of graphs in optimal time. In particular, we provide tight results for bipartite tori, meshes, hypercubes, Knödel graphs, circulant graphs. We also propose several open problems and conjectures.     

Intensive Parenting: Fertility and Breastfeeding Duration in the United States

Using 30 years of longitudinal data from a nationally representative cohort of women, we study the association between breastfeeding duration and completed fertility, fertility expectations, and birth spacing. We find that women who breastfeed their first child for five months or longer are a distinct group. They have more children overall and higher odds of having three or more children rather than two, compared with women who breastfeed for shorter durations or not at all. Expected fertility is associated with initiating breastfeeding but not with how long mothers breastfeed. Thus, women who breastfeed longer do not differ significantly from other breastfeeding women in their early fertility expectations. Rather, across the life course, these women achieve and even exceed their earlier fertility expectations. Women who breastfeed for shorter durations (1–21 weeks) are more likely to fall short of their expected fertility than to achieve or exceed their expectations, and they are significantly less likely than women who breastfeed for longer durations (≥22 weeks) to exceed their expected fertility. In contrast, women who breastfeed longer are as likely to exceed as to achieve their earlier expectations, and the difference between their probability of falling short versus exceeding their fertility expectations is relatively small and at the boundary of statistical significance (p = .096). These differences in fertility are not explained by differences in personal and family resources, including family income or labor market attachment. Our findings suggest that breastfeeding duration may serve as a proxy for identifying a distinct approach to parenting. Women who breastfeed longer have reproductive patterns quite different than their socioeconomic position would predict. They both have more children and invest more time in those children.     

A cognitive-behavioral plus exercise intervention for older adults with chronic back pain: race/ethnicity effect?

This pilot study examined the feasibility and potential efficacy of a self-management program for seniors with chronic back pain and assessed for possible race/ethnicity differences in program impact. Sixty-nine seniors (24 African Americans, 25 Hispanics, and 20 non-Hispanic Whites) enrolled in the 8-wk community-based program. Efficacy outcomes included pain-related disability as measured by the Roland Morris Disability Questionnaire (RMDQ), pain intensity, pain self-efficacy, depressive symptoms, social activity, and functional status. Eighty percent of enrollees completed the program. Clinically important decreases in RMDQ scores were found for non-Hispanic White (adjusted change score = -3.53), African American (-3.89), and Hispanic (-8.45) participants. Improvements in all other outcomes were observed, but only for Hispanic participants. Results confirm that implementation of the protocol in urban senior centers is feasible, and the program shows potential efficacy. The race/ethnicity differences observed in the current study merit further investigation.     

Reimagining social work case studies: a social work—creative writing collaboration

This paper describes a joint social work and creative writing project which analysed case studies from textbooks on reading lists for the Bachelor of Social Work course at Edith Cowan University. The textbook case studies were analysed from the perspectives of both social work and literary craft and it was found that they presented simplified scenarios which were limited in terms of diversity and rarely portrayed depth or complexity. The case studies were also often bereft of information about social workers’ or service users’ human qualities and frequently portrayed service users in terms of the problems they presented to the social worker. The authors argue that depicting social workers and service users in this way can create the impression that social work is a distanced procedural activity and can also serve to distance service users’ lives and experiences from social work students. Drawing on research in creative writing craft, as well as analysis of the textbook case studies, principles for writing engaging text-book case studies were developed and the paper concludes by arguing for the use of these principles when crafting social work case studies.